A: Your program shall always read input from stdin (Standard Input) and write output to stdout (Standard Output). For example, you can use ‘scanf‘ in C or ‘cin‘ in C++ to read from stdin, and use ‘printf‘ in C or ‘cout‘ in C++ to write to stdout.
You shall not output any extra data to standard output other than that required by the problem, otherwise you will get a "Wrong Answer".
User programs are not allowed to open and read from/write to files. You will get a "Runtime Error" or a "Wrong Answer" if you try to do so.
Here is a sample solution for problem 1000 using C++/G++: